Example of VirtIO I/F Use in the native & virtual AGL Apr 22, 2021 Future Steps SAT/ Profile- Showed in previous F2F Virt-EG Scope SAT Scope Specified EG’s Scope SAT meeting in Mar First Step is to identify the devices necessary and important for AGL and assign priority! Use VirtIO driver I/F as lower I/F makes userspace We would like to lead the whole Implementation (such as IVI activity and work together with PR, IC) independent from SAT, IVI-EG, IC-EG and etc.. IVI PR / IC / Telematics lower level device driver implementation! Userspace Kernel VirtIO driver I/F VirtIO Front End Device Driver Physical Device Driver Concept For most of devices, Linux Device Subsystem are used as the virtio driver I/F to the userspace. IVI PR Application /IC Device driver /Telematics interchangeability in Userspace AGL Userspace - SoC A SoC B … in native AGL Kernel - Virt AGL Native AGL Kernel VirtIO driver I/F Linux Device Subsystem by simple configuration change in device tree Virtio-xxx VirtIO Front End Physical SoC 1 Frontend Device Driver Device Driver SoCDD N Driver Device Using the Linux Device Subsystem Driver will allow userspace to have one Device unique interface no matter in SoC Device tree native or virtual platform. HW dependency will be absorbed under the Linux Device Subsystem Block Device Application • Mature Standard Linux Block Subsystem are AGL commonly used by virtualization world and User native world without hardware dependency. /dev/block/xxxxx • Data read/write/trim operation enabled by Kernel Block Subsystem block subsystem have already covered basic VFS/Filesystem use cases in automotive • With the existing I/F, abstraction of hardware Generic Block Layer has been already achieved and few work IO Scheduler need to be done. Physical Device Virtio-Block PhysicalDriver Device A Front End Driver PhysicalDriver Device B Driver C Native Virtualization 4 Input Device Application • Standard “evdev” generic input event interface AGL • passed events generated in kernel straight to User the program with same event codes on all /dev/input/eventX architectures and HW-independent. Kernel Input Subsystem • Additional Extension is needed for automotive use Input event handler • Multi-touch protocol has been supported in input subsystem but extension of virtio-input Input core front end is needed (planned in Virt-EG activities). • Current input subsystem doesn’t cover the calibration/sensitivity setting and need to be Physical Device Virtio-Input extended to support the use case. PhysicalDriver Device A Front End Driver PhysicalDriver Device B Driver C Native Virtualization 5 RPMB Device • What is RPMB • RPMB is Replay Protected Memory Block • A write protected region on certain flash devices such as eMMC and UFS. • Fixed size partition (128KB ~ 16MB) with counter and can only be accessed by Trustzone • Use Case: Anti roll-back and replay attack protection • Protect from downgrading software • Protect from unauthorized device unlocking (times of attempts to unlock is recorded in RPMB) • Secure boot (partitions write protection) 6 RPMB Device Application • Fragmented I/F for rpmb AGL • MMC: MMC_IOC_CMD ioctl User /dev/rpmbX • UFS: SG_IO ioctl Kernel • Along with standardization of VirtIO- RPMB, standardization of Linux RPMB Subsystem RPMB subsystem is progressing • Common RPMB subsystem with one ioctl (+simulator) /dev/rpmbX • Apply the same RPMB subsystem Physical Device VirtIO-RPMB to native case will help the device PhysicalDriver Device A Front End Driver PhysicalDriver Device B abstraction in the way that one Driver C unique interface is used from userspace Native Virtualization 7 Summary • VirtIO utilize the standard Linux Device Subsystem to provide unique interface to userspace independent from HW. (Linux Device Subsystem can be seen as VirtIO driver I/F to userspace) • Benefiting from the VirtIO standardization, Linux subsystem is also growing to a more mature common interface that different vendors can take advantage of it. • Same idea can be applied to native case to absorb HW difference under Linux Device Subsystem and use common user-kernel interface. Block Device Input Device RPMB Device Standard & Mature Standard but Need Extension for Under standardization Automotive Production Use Case 8.